Late hyaluronidase injection in local anesthesia: Morphofunctional evaluation in rat sciatic nerve block

Area of Science:

• Anesthesiology
• Histology
• Pharmacology

Background:

• Hyaluronidase (HYAL) enhances local anesthetic duration but may cause adverse effects.
• Assessing tissue alterations and functional effectiveness of a late HYAL injection protocol is crucial.

Purpose of the Study:

• To evaluate tissue alterations from a local anesthetic protocol involving late HYAL injection.
• To confirm the functional effectiveness of this protocol.

Main Methods:

• Sciatic nerve block in rats using lidocaine (LID) with epinephrine.
• Administered HYAL 30 minutes post-LID (LID/HYAL group) or vehicle (LID/V control group).
• Histological analysis of nerve and surrounding tissues at various time points post-injection.

Main Results:

• No significant difference in local inflammation between LID/HYAL and LID/V groups.
• Nerve fiber integrity was preserved, with reversible tissue disorganization observed.
• The HYAL protocol prolonged the anesthetic effect (P < 0.05).

Conclusions:

• Late HYAL administration before the end of LID block does not cause irreversible morphological changes.
• This protocol effectively prolongs the anesthetic duration of lidocaine.